> For the complete documentation index, see [llms.txt](https://gabriel-j-shapiro.gitbook.io/metalex-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gabriel-j-shapiro.gitbook.io/metalex-docs/protocol-reference/extensions.md).

# Certificate extensions

Extensions are pluggable metadata contracts registered on a `CyberCertPrinter` for a given security type. They produce the instrument-specific attributes built into the cyberCERT's `tokenURI` and enforce any instrument-specific rules at issuance time.

Each extension is its own UUPS-upgradeable contract.

## ShareExtension

Preferred and Common stock. NVCA-aligned series terms.

* Liquidation preference
* Conversion ratio (preferred ↔ common)
* Anti-dilution (broad-based weighted average, full ratchet, none)
* Voting power
* Series identifier ("Series Seed", "Series A", "Series Pre-A", etc.)

## SAFEExtension

Simple Agreement for Future Equity.

* Custom provisions field
* Valuation cap
* Discount
* MFN flag
* Conversion trigger event

Feeds [`SafeCertificateConverter`](/metalex-docs/protocol-reference/contracts/safecertificateconverter.md).

## ACESAFEExtension

ACE-specific SAFE variant for token-to-equity conversions, used by [PumpCorpFactory](/metalex-docs/protocol-reference/factories.md#pumpcorpfactory).

## SAFTExtension / SAFTExtensionV2

Simple Agreement for Future Tokens.

* Unlock schedule
* Cliff period
* Vesting interval
* Token (or token-yet-to-be-deployed) reference

## SAFTEExtension / SAFTEExtensionV2

Simple Agreement for Future Tokens or Equity. Combines SAFT and SAFE attributes; the conversion path is determined by which trigger event fires first.

## TokenWarrantExtension / TokenWarrantExtensionV2

Token warrants.

* Exercise price
* Token-amount calculation method (fixed, pro rata, formula)
* Unlock parameters
* Expiration

## Registering an extension

```solidity
certPrinter.setExtension(SECURITY_TYPE_SAFE, address(safeExtension));
```

A `CertIssuance.extensionData` is then `abi.encode`d to the extension's expected struct.


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